Question

The bob of a simple pendulum is a spherical hollow ball filled with water. A plugged hole near the bottom of the oscillating bob gets suddenly unplugged. During observation, till water is coming out, the time period of oscillation would

• A. first increases then decrease back to the original value
• B. first decreases then increase back to the original value
• C. remains unchanged
• D. increases towards a saturation value

Answer 1

Answer: (A)

and $T_1>T_2$
Hence, time period first increases and then decreases to the original value.
The given system is like a simple pendulum, whose effective length between the point of suspension and the center of gravity of the hanging body is changing.
When water slowly flows out, the sphere, the C.G. of system is lowered & hence L increase